3D printing block assembly



FIG. 1 is a perspective view of a 3D printing block assembly;

FIG. 2 is a front view thereof;

FIG. 3 is a left view thereof;

FIG. 4 is a right view thereof;

FIG. 5 is a rear view thereof; and,

FIG. 6 is a top view thereof. 

CLAIM The ornamental design for a 3D printing block assembly, as shown. 